In the past polystyrene has been blended with high styrene content 1,3-butadiene/styrene multiblock copolymers for thermoforming. Generally (S-B)x star block copolymers having a 75-80% styrene content were utilized. When linear block copolymers such as S-B-S or B-S-B-S type have been used, however, these resins were not suitable for thermoforming as when they were blended with polystyrene the thermoformed blends lacked high clarity and/or high impact strength or flexibility.